Scientists find the key to why greens cut risk of heart disease

Eeating your greens really is good for you. A pigment found in dark green vegetables such as broccoli, sprouts and spinach helps to protect against hardening of the arteries, scientists reported yesterday.

The substance, lutein, prevents blood vessels clogging up, a condition that increases the risk of heart disease, Californian researchers have found. Arteries harden five times faster among people with low levels of lutein in the blood.

Scientists already know there is a link between eating fruit and vegetables and low levels of cardiovascular disease and recommend eating five portions a day. But lutein could be among the first components to be identified that helps make vegetables healthy.

Professor James Dwyer, who led the research at the University of California, said: "There is mounting evidence that increased intake of vegetables and fruits is protective against cardiovascular disease. We may have identified one of the many components of vegetables that account for [these] effects."

He added that the benefit remained after the vegetables had been cooked. Lutein is also present in lettuce, cucumber, peas, asparagus, avocado, green beans, cabbage and celery. The substance, a natural colouring agent found in many foods, has already been linked with healthy eyesight.

Scientists monitored 480 men and women, none at risk of heart disease, to measure the rate of thickening of the arteries. Volunteers who ate diets high in lutein-rich food proved to be much less at risk of long-term hardening of the arteries. Over an 18-month period, the scientists measured the thickness of the walls of an artery in the neck. The rate of thickening was five times faster among patients with low levels of lutein.

In laboratory tests, scientists found that layers of arterial cells "treated" with lutein were much more resistant to the effects of cholesterol, which causes the thickening.

But the scientists found no benefits from beta carotene, another nutrient that has been suggested as preventing or slowing the progress of hardening of the arteries.

The British Nutrition Foundation welcomed the study and said it emphasised the importance of a balanced diet and supported its recommendation to eat five portions of fruit or vegetables a day.